Will come within 1.4 million kilometers of the surface of the Sun.

In late September, astronomers using a telescope in Russia spotted a new comet, now going by the name of C/2012 S1 (ISON). It's currently not visible without some fairly high-end hardware, but the preliminary calculations of its trajectory suggest that it's likely to pass close to both the Earth and Sun about a year from now, a path that has the potential to provide a once-in-a-lifetime show.

According to a number of articles that appeared at about the same time, the comet's orbit is taking it nearly directly at the Sun, and will get within 1.4 million kilometers of the Sun's surface in November of next year, which should provide a lot of heat to melt the surface and expel gas from the comet. By January, it will be about 60 million kilometers from Earth.

That combination could, according to some estimates, leave the comet looking brighter than the full Moon, and could make it the brightest comet on record. But the actual brightness will depend heavily on details like the comet's composition and how much of its material gets ejected once it heats up. There have been some hotly anticipated comets that didn't live up to expectations, and a few that have turned out to be pleasant surprises. But if ISON is anywhere close to some of the higher estimates, we'll be in for quite a show.

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This writeup (and *all* the others linked) neglects to mention the very real possibility that the comet could be torn apart at its perihelion (or even long before then). Comets are big, dirty, sometimes loosly packed and rubbly iceballs. Many sungrazers don't come around a second time because they just don't make the trip the first time.

I would very, very much like Ars to post an article as the event is closer on how/when people can look at this when it happens.

I just fired up my Starry Night program to see where in the sky the comet will be at the times it may be most visible (From my location in Michigan). Sometime around November 1, 2013 the comet will rise In the East at around 4am Eastern Time. It should be around 6 degrees south of Mars. At this time it may not be bright enough to the naked eye. Over the month, It will start rising later, and more towards the SE, while getting brighter every day. During this time, the comet's tail should be getting longer and brighter (not sure if the tail will be bright enough to the naked eye).

Here's a date to look forward to. On Nov 24th, 2013, right before sunrise. The comet, Saturn and Mercury will form a nice triangle only separated by 4 degrees, all three visible to the naked eye (if things to as planned with the comet).

If the comet survives the pass by the sun on the 29th, it will again appear just before sunrise to the ESE. It will rise earlier and move towards the East each passing day (while also getting a bit dimmer). If nothing catastrophic happens to the comet, it may be a naked eye comet for the good part of two months (Nov 1, 2013 - Jan 1, 2014).

I'm sure that there will be plenty of updates, if not here, elsewhere! I am sure to have my camera and telescope out trying to get pictures. It should be bright enough a camera on tripod will give some good widefield views of the comet.

BTW...when they say "bright as the full moon" don't be fooled. That is only when the comet is very close to the sun. For those interested they had the chart at the bottom with their news release. Magnitude is how bright the comet is. Depending on how dark your skies are, the comet may be visible to the naked eye at around Magnitude 4-5. The "elongation" is just the amount of separation between the Sun and comet in degrees when viewing from the Earth.

7682 posts | registered Mar 26, 1999

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